Methods for the production of radiolabelled synthetic polymers are known in the art. Traditional methods include the use of chemical linkers which may attach radionuclides by either salt linkage (i.e. similar to ion exchange resins) or by the use of chelate chemistry. Typically these methods suffer from either low retention of radionuclide or low specific activity due to the limited density of labelling obtainable on the polymer (respectively). More recently chelate derivatives of detergents have been used to radiolabel the surface of carbon nanotubes, but these suffer the same limitation of low rate of labelling as for other chelate derivatives, as well as the low biological tolerance of such detergents [Liu et al, Nature Nanotechnology 2:47-52 (2007)]. Another limitation of the use of chelate chemistry is that a given chelating functionality is not suitable for a wide range of different metallic radionuclides. Changing the metal often necessitates changing the chemistry of the chelate. The synthetic radiolabelled polymers may find use in various medical and therapeutic areas. As an example, several types of implants are used in medicine for the treatment of cardiovascular disease and cancer. Thus for example, stents (short cylindrical tubes) are implanted in coronary arteries to increase vessel patency, and the synthetic polymer surface of some stents may include an inhibitor of restenosis to prevent recurrence of an occlusion in the vessel. Endovascular brachytherapy with radioisotopes is one method for preventing reocclusion during the short post-operative period, in which the stent includes a radioisotope to inhibit proliferation of smooth muscle cells. In the treatment of cancer, radiolabelled synthetic polymers may be used in several forms e.g. microspheres, that can be locally instilled in the afferent blood supply to a selected organ, for the purpose of regional delivery of a therapeutic dose of a radioisotope that can ablate a tumour. High levels of specific activity of labelling on the polymer and strong retention of the radionuclide on the polymer are desirable in such a therapeutic strategy, in order that a large dose of activity is delivered in a small amount of material and the effect of the radiation can be reliably restricted to the target tissue. Methods known in the art for radiolabelling synthetic polymers are limited by 1) the degree to which the synthetic polymer may be labelled and or 2) the avidity of the labelling, and 3) in their application to a wide range of different metallic radionuclides.
There is a need for improved methods of preparing radiolabelled synthetic polymers that overcome or avoid one or more disadvantages or limitations of the known methods.